#ifndef PERLIN_H
#define PERLIN_H

namespace anime {
    // based on the java reference implementation published
    // on http://mrl.nyu.edu/~perlin/noise/
    // updated on 13/7/2005

    class Perlin
    {
    public:

        /// 3D Perlin noise
        /// return a value in the 0..1 range with period 255
        static double Noise(double x, double y, double z) {
            int X = (int)floor(x) & 255,                  // FIND UNIT CUBE THAT
            Y = (int)floor(y) & 255,                  // CONTAINS POINT.
            Z = (int)floor(z) & 255;
            x -= floor(x);                                // FIND RELATIVE X,Y,Z
            y -= floor(y);                                // OF POINT IN CUBE.
            z -= floor(z);
            double u = fade(x),                                // COMPUTE FADE CURVES
            v = fade(y),                                // FOR EACH OF X,Y,Z.
            w = fade(z);
            int A = P(X  )+Y, AA = P(A)+Z, AB = P(A+1)+Z,      // HASH COORDINATES OF
            B = P(X+1)+Y, BA = P(B)+Z, BB = P(B+1)+Z;      // THE 8 CUBE CORNERS,

            return lerp(w, lerp(v, lerp(u, grad(P(AA  ), x  , y  , z   ),  // AND ADD
                                        grad(P(BA  ), x-1, y  , z   )), // BLENDED
                                lerp(u, grad(P(AB  ), x  , y-1, z   ),  // RESULTS
                                     grad(P(BB  ), x-1, y-1, z   ))),// FROM  8
                        lerp(v, lerp(u, grad(P(AA+1), x  , y  , z-1 ),  // CORNERS
                                     grad(P(BA+1), x-1, y  , z-1 )), // OF CUBE
                             lerp(u, grad(P(AB+1), x  , y-1, z-1 ),
                                  grad(P(BB+1), x-1, y-1, z-1 ))));
        }
        static double fade(double t) { return t * t * t * (t * (t * 6 - 15) + 10); }
        static double lerp(double t, double a, double b) { return a + t * (b - a); }
        static double grad(int hash, double x, double y, double z) {
            int h = hash & 15;                      // CONVERT LO 4 BITS OF HASH CODE
            double u = h<8 ? x : y,                 // INTO 12 GRADIENT DIRECTIONS.
            v = h<4 ? y : h==12||h==14 ? x : z;
            return ((h&1) == 0 ? u : -u) + ((h&2) == 0 ? v : -v);
        }
        static int P(int i)
        {
            static int p[512]= { 151,160,137,91,90,15,
                                 131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
                                 190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
                                 88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
                                 77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
                                 102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
                                 135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
                                 5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
                                 223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
                                 129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
                                 251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
                                 49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
                                 138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180,
                                 151,160,137,91,90,15,
                                 131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
                                 190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
                                 88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
                                 77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
                                 102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
                                 135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
                                 5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
                                 223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
                                 129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
                                 251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
                                 49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
                                 138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180
                             };
            return p[i];
        }
    };
}
#endif // PERLIN_H
